Pianotech

  • 1.  Damper lever spring tensions

    Registered Piano Technician
    Posted 07-07-2019 21:23
    Hi List,
    I remember a tip or an article from Don Mannino several years ago about calibrating the spring tensions for damper levers. Does anyone have a set of figures for gram resistance that they use, or consider a range too great or too little? Or perhaps recall which Journal issue Don wrote about this?

    Thanks all. For every contribution.
    Joe Wiencek


  • 2.  RE: Damper lever spring tensions

    Posted 07-07-2019 23:30
    I had an interesting experience in regard to too much damper lever spring tension:
    the last Renner back action kit I installed I used the recommended spring tensions ( can't recall the numbers, sorry) in the instructions.
    when I finished regulating I found that when I released the sustain pedal all of the dampers lifted slightly.
    it took a while to figure what was happening but what it was - the combined lift lever spring tensions were greater than the damper tray return spring that came with the kit.
    slight massaging of the springs and going to hardware store to get a stronger coil spring that fit in the tray fixed it.
    sorry I don't have numbers for you.

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    [Gene] [Nelson] [RPT]
    [Sacramento Valley Chapter]
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  • 3.  RE: Damper lever spring tensions

    Registered Piano Technician
    Posted 07-08-2019 16:46
    Gene,
    That is an intriguing result. I admit I'm having a hard time visualizing how the dampers were lifting. Which portion of the travel did that occur?
    I should have specified that in my case it's a set of upright damper levers (Steinway db flange.)

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    Joe Wiencek

    New York NY
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  • 4.  RE: Damper lever spring tensions

    Posted 07-08-2019 17:11
    Sorry if I missed the upright. Not sure what to say about that.
    I had a hard time visualizing the problem too. Lots of scratching the head time.
    Try to visualize the damper lever springs pushing from the tray where they mount right behind the lift lever flange as well as against the lift levers themselves. If the total lift lever spring tension of all 67 or 68 springs is strong enough, they will tend to rotate the damper tray in the lift direction when the sustain pedal is disengaged.
    If the tray return spring isnt strong enough the dampers will lift slightly.

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    [Gene] [Nelson] [RPT]
    [Sacramento Valley Chapter]
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  • 5.  RE: Damper lever spring tensions

    Posted 07-08-2019 17:37
    The grand dampers lift because the underlevers are supported by the damper wires. So the stationary underlevers cause the springs to lift the tray. You need to install another spring at the bass break. Especially if the tray pivot is inline with the flange centers.

    It's not upright damper spring tension that mutes the strings, all you need is minimal pressure. A heavier damper head is what is needed as Del has pointed out.

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    Regards,

    Jon Page
    mailto:jonpage@pianocapecod.com
    http://www.pianocapecod.com
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  • 6.  RE: Damper lever spring tensions

    Posted 07-08-2019 17:51
    Your right Jon.
    And the tray/lever flange rotations were concentric.
    This may be why the suggested spring tension numbers from Renner were a bit too strong.
    I managed to locate a stronger return spring that fit so I could keep it close to the pitman. 
    I avoid end of tray return springs.


    Sent from Yahoo Mail for iPhone





  • 7.  RE: Damper lever spring tensions

    Registered Piano Technician
    Posted 07-08-2019 17:52
    From the Renner technical manual:



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    Benjamin Sanchez, RPT
    Piano Technician / Artisan
    (805)315-8050
    www.professional-piano-services.com
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  • 8.  RE: Damper lever spring tensions

    Posted 07-08-2019 18:38
    Thx for posting the Renner #'S
    one alternate method I've used in the past was to support the assembled tray upside down and adjust spring tension so the lift lever was barely held against the underlever felt, this worked ok and I never had that problem mentioned above.
    back to upright dampers, sorry to distract.

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    [Gene] [Nelson] [RPT]
    [Sacramento Valley Chapter]
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